Generate Checkstyle Report As Standalone

You can also generate the Checkstyle report by explicitly executing the checkstyle:checkstyle goal from the command line. It is not required to specify the Checkstyle Plugin in your pom.xml unless you want to use a specific configuration.

mvn checkstyle:checkstyle

To specifically configure the Checkstyle Plugin, you need to the add it in the <build> section of your pom.xml as shown in the sample below.